Thermoacoustic coupling in liquid-fueled dry low emission gas turbine combustors for electrical power generation

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This Collaborative Research and Development (CRD) project between the University of Toronto Institute for Aerospace Studies (UTIAS) Experimental Engines (E2) Lab, GE Canada, and the GE Global Research Center (GRC) focuses on preventing thermoacoustic instabilities in gas turbine engines used for electrical power generation. The specific focus is on instabilities arising during the use of liquid fuel in 'dual-fuel' dry low emission combustors. These instabilities are a primary challenge in the design and deployment of robust, low-emission, fuel-flexible power generation engines.Laser and optical measurement techniques developed in the E2 Lab will be deployed at GE GRC to obtain data in realistic gas turbine hardware operating at practical conditions, viz. pressures up to 1.5 MPa, reactant temperatures up to 625 K, combustor thermal powers exceeding 1 MW. The diagnostics to be deployed include high-speed stereoscopic particle image velocimetry (SPIV), fuel droplet scattering, and multi-species chemiluminescence to obtain gas-phase and liquid velocity fields, fuel spray distributions, and heat release rate distributions, respectively. Five experimental campaigns at GRC are planned over the duration of the project, covering various phenomena and conditions. To our knowledge, the resultant data will constitute the most complete experimental information obtained on thermoacoustic instabilities at practical gas turbine conditions.These data will be mined to explain the flow/fuel/flame/pressure coupling that sets the thermoacoustic forcing in various situations. For example, we will explain the initial coupling that allows high-amplitude oscillations to grow from noise. We also will explain the coupling driving the final sustained high-amplitude oscillations. These mechanistic insights will be used to construct a reduced order semi-empirical model for the thermoacoustic forcing. Ultimately, the data will be used to understand thermoacoustic instabilities, improve combustor design, and develop best practices for simulating thermoacoustic instabilities using computationalfluid dynamics.